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Power drop immediately once in Transmit ??

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  • g0lgj
    Hi I have a Ts-50 that immediately drop power once the mic is keyed. It drops from 100W on all bands too nothing in about a second. No fan coming on ? This is
    Message 1 of 7 , Jul 3, 2007
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      Hi I have a Ts-50 that immediately drop power once the mic is keyed.
      It drops from 100W on all bands too nothing in about a second.
      No fan coming on ?
      This is into a dummy load.
      Can it be a SWR issue with lpf board ?

      Any help gratefully received.

      Mark G0LGJ
    • Fred
      My first suggestion is to check the power cord fromm the supply to the radio, specifically the fuses, for corrosion. Sounds like your not getting enough
      Message 2 of 7 , Jul 3, 2007
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        My first suggestion is to check the power cord fromm the supply to
        the radio, specifically the fuses, for corrosion. Sounds like your
        not getting enough amperage to the radio.

        Fred - KK5AA



        --- In Kenwood_TS50@yahoogroups.com, "g0lgj" <markg0lgj@...> wrote:
        >
        > Hi I have a Ts-50 that immediately drop power once the mic is keyed.
        > It drops from 100W on all bands too nothing in about a second.
        > No fan coming on ?
        > This is into a dummy load.
        > Can it be a SWR issue with lpf board ?
        >
        > Any help gratefully received.
        >
        > Mark G0LGJ
        >
      • g0lgj
        Hi Fred thanks for suggestions had looked at that as mentioned in previous posts. What I have found since is that the power seems to come back and oscillate
        Message 3 of 7 , Jul 4, 2007
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          Hi Fred thanks for suggestions had looked at that as mentioned in
          previous posts.

          What I have found since is that the power seems to come back and
          "oscillate" Off and on about every 1.5 seconds.

          Took the PA and lpf board apart and checked for dry joints nothing.
          Heatsink compound very dry thought that might be it but to no avail.

          Back to the drawing board.

          73 de Mark G0LGJ




          --- In Kenwood_TS50@yahoogroups.com, "Fred" <poppafred@...> wrote:
          >
          > My first suggestion is to check the power cord fromm the supply to
          > the radio, specifically the fuses, for corrosion. Sounds like your
          > not getting enough amperage to the radio.
          >
          > Fred - KK5AA
          >
          >
          >
          > --- In Kenwood_TS50@yahoogroups.com, "g0lgj" <markg0lgj@> wrote:
          > >
          > > Hi I have a Ts-50 that immediately drop power once the mic is keyed.
          > > It drops from 100W on all bands too nothing in about a second.
          > > No fan coming on ?
          > > This is into a dummy load.
          > > Can it be a SWR issue with lpf board ?
          > >
          > > Any help gratefully received.
          > >
          > > Mark G0LGJ
          > >
          >
        • Dick Mobley
          This seems to be a common problem with the TS-50. It is often caused by defective semiconductors in a –6.3VDC reference oscillator used to regulate the
          Message 4 of 7 , Jul 4, 2007
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            This seems to be a common problem with the TS-50. It is often caused by
            defective semiconductors in a –6.3VDC reference oscillator used to regulate
            the transmit power out. The main problem is the components are surface
            mounted on the bottom of the TX-RX board.

            The voltage is generated and regulated by Q51; Q52 and Q53. Q52 and Q53
            (2SC2712(Y)) are the same type so you might get lucky by simply swapping the
            two. Q51 is a 2SA1162(Y). If you have the schematic the circuit is near
            connector CN18 at the lower left of the TX-RX board drawing.

            It is not impossible to repair but the surface mounted components can make
            it challenging. I have fixed two rigs with this problem and have never
            changed any capacitors but I can see where that could also be a problem.

            It is possible to meter the –6.2VDC at IC11 to see how stable it is. After
            passing through L58 at the voltage source the voltage is dropped from –6.3
            to –6.2VDC.

            Good luck with the project.

            Dick
            AL7B

            -----Original Message-----
            From: Kenwood_TS50@yahoogroups.com [mailto:Kenwood_TS50@yahoogroups.com]On
            Behalf Of g0lgj
            Sent: Wednesday, July 04, 2007 2:46 AM
            To: Kenwood_TS50@yahoogroups.com
            Subject: [Kenwood_TS50] Re: Power drop immediately once in Transmit ??

            Hi Fred thanks for suggestions had looked at that as mentioned in
            previous posts.

            What I have found since is that the power seems to come back and
            "oscillate" Off and on about every 1.5 seconds.

            Took the PA and lpf board apart and checked for dry joints nothing.
            Heatsink compound very dry thought that might be it but to no avail.

            Back to the drawing board.

            73 de Mark G0LGJ

            --- In Kenwood_TS50@yahoogroups.com <mailto:Kenwood_TS50%40yahoogroups.com>
            , "Fred" <poppafred@...> wrote:
            >
            > My first suggestion is to check the power cord fromm the supply to
            > the radio, specifically the fuses, for corrosion. Sounds like your
            > not getting enough amperage to the radio.
            >
            > Fred - KK5AA
            >
            >
            >
            > --- In Kenwood_TS50@yahoogroups.com
            <mailto:Kenwood_TS50%40yahoogroups.com> , "g0lgj" <markg0lgj@> wrote:
            > >
            > > Hi I have a Ts-50 that immediately drop power once the mic is keyed.
            > > It drops from 100W on all bands too nothing in about a second.
            > > No fan coming on ?
            > > This is into a dummy load.
            > > Can it be a SWR issue with lpf board ?
            > >
            > > Any help gratefully received.
            > >
            > > Mark G0LGJ
            > >
            >



            [Non-text portions of this message have been removed]
          • Clif
            It s the -6v converter ala TS850. The TS50 has exactly the same -6 converter circuit but it s not on a small PCB and easily replaceable as in the TS850. It s a
            Message 5 of 7 , Jul 4, 2007
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              It's the -6v converter ala TS850. The TS50 has exactly the same -6
              converter circuit but it's not on a small PCB and easily replaceable
              as in the TS850.

              It's a bit of a pain to get to the circuit for troubleshooting so I
              just replace the main parts en-mass and go on. It's on the back left
              side of the TX/RX board for reference. Schematic on Pg 119 bottom left
              corner of the TX/RX board.

              Here's the list;
              Q51 - 2SA1162
              Q52,53 - 2SC2712
              C194,196,197 - 47uf 16v Surface mount electrolytics

              That's always fixed them for me.

              Clif

              --- In Kenwood_TS50@yahoogroups.com, "g0lgj" <markg0lgj@...> wrote:
              >
              > Hi Fred thanks for suggestions had looked at that as mentioned in
              > previous posts.
              >
              > What I have found since is that the power seems to come back and
              > "oscillate" Off and on about every 1.5 seconds.
              >
              > Took the PA and lpf board apart and checked for dry joints nothing.
              > Heatsink compound very dry thought that might be it but to no avail.
              >
              > Back to the drawing board.
              >
              > 73 de Mark G0LGJ
              >
              >
              >
              >
              > --- In Kenwood_TS50@yahoogroups.com, "Fred" <poppafred@> wrote:
              > >
              > > My first suggestion is to check the power cord fromm the supply to
              > > the radio, specifically the fuses, for corrosion. Sounds like your
              > > not getting enough amperage to the radio.
              > >
              > > Fred - KK5AA
              > >
              > >
              > >
              > > --- In Kenwood_TS50@yahoogroups.com, "g0lgj" <markg0lgj@> wrote:
              > > >
              > > > Hi I have a Ts-50 that immediately drop power once the mic is keyed.
              > > > It drops from 100W on all bands too nothing in about a second.
              > > > No fan coming on ?
              > > > This is into a dummy load.
              > > > Can it be a SWR issue with lpf board ?
              > > >
              > > > Any help gratefully received.
              > > >
              > > > Mark G0LGJ
              > > >
              > >
              >
            • g0lgj
              Hi Fred and Dick thanks for the suggestions. taking the board out and looking at components looks as the boards has got very hot and bubbled in this area
              Message 6 of 7 , Jul 4, 2007
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                Hi Fred and Dick thanks for the suggestions.
                taking the board out and looking at components looks as the boards has
                got very hot and "bubbled" in this area bottom of tx/rx board located
                underside or VR7 is this the correct area. I have cct diag and found
                that area but need to find a cct layout.

                Thanks again for you assistance.

                Mark

                --- In Kenwood_TS50@yahoogroups.com, "Dick Mobley" <dick@...> wrote:
                >
                > This seems to be a common problem with the TS-50. It is often caused by
                > defective semiconductors in a –6.3VDC reference oscillator used to
                regulate
                > the transmit power out. The main problem is the components are surface
                > mounted on the bottom of the TX-RX board.
                >
                > The voltage is generated and regulated by Q51; Q52 and Q53. Q52 and Q53
                > (2SC2712(Y)) are the same type so you might get lucky by simply
                swapping the
                > two. Q51 is a 2SA1162(Y). If you have the schematic the circuit is
                near
                > connector CN18 at the lower left of the TX-RX board drawing.
                >
                > It is not impossible to repair but the surface mounted components
                can make
                > it challenging. I have fixed two rigs with this problem and have never
                > changed any capacitors but I can see where that could also be a problem.
                >
                > It is possible to meter the –6.2VDC at IC11 to see how stable it is.
                After
                > passing through L58 at the voltage source the voltage is dropped
                from –6.3
                > to –6.2VDC.
                >
                > Good luck with the project.
                >
                > Dick
                > AL7B
                >
                > -----Original Message-----
                > From: Kenwood_TS50@yahoogroups.com
                [mailto:Kenwood_TS50@yahoogroups.com]On
                > Behalf Of g0lgj
                > Sent: Wednesday, July 04, 2007 2:46 AM
                > To: Kenwood_TS50@yahoogroups.com
                > Subject: [Kenwood_TS50] Re: Power drop immediately once in Transmit ??
                >
                > Hi Fred thanks for suggestions had looked at that as mentioned in
                > previous posts.
                >
                > What I have found since is that the power seems to come back and
                > "oscillate" Off and on about every 1.5 seconds.
                >
                > Took the PA and lpf board apart and checked for dry joints nothing.
                > Heatsink compound very dry thought that might be it but to no avail.
                >
                > Back to the drawing board.
                >
                > 73 de Mark G0LGJ
                >
                > --- In Kenwood_TS50@yahoogroups.com
                <mailto:Kenwood_TS50%40yahoogroups.com>
                > , "Fred" <poppafred@> wrote:
                > >
                > > My first suggestion is to check the power cord fromm the supply to
                > > the radio, specifically the fuses, for corrosion. Sounds like your
                > > not getting enough amperage to the radio.
                > >
                > > Fred - KK5AA
                > >
                > >
                > >
                > > --- In Kenwood_TS50@yahoogroups.com
                > <mailto:Kenwood_TS50%40yahoogroups.com> , "g0lgj" <markg0lgj@> wrote:
                > > >
                > > > Hi I have a Ts-50 that immediately drop power once the mic is keyed.
                > > > It drops from 100W on all bands too nothing in about a second.
                > > > No fan coming on ?
                > > > This is into a dummy load.
                > > > Can it be a SWR issue with lpf board ?
                > > >
                > > > Any help gratefully received.
                > > >
                > > > Mark G0LGJ
                > > >
                > >
                >
                >
                >
                > [Non-text portions of this message have been removed]
                >
              • james27613
                hi mark, I ve got the service manual and schematics in 400dpi pdf file fee to d/l here: http://www.radioamateur.eu/KENWOOD.html they have manuals no cost from
                Message 7 of 7 , Jul 5, 2007
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                  hi mark,

                  I've got the service manual and schematics
                  in 400dpi pdf file fee to d/l here:

                  http://www.radioamateur.eu/KENWOOD.html

                  they have manuals no cost from the big three
                  if you have a manual to share please upload it
                  to their site.

                  good luck with your repair.

                  73 james ke4drn
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